Presenting an Alternative to BOD

Three lab managers discuss their switch to TOC analysis in a no-charge August webcast


Next month, a webcast will help Water Environment Federation (WEF; Alexandria, Va.) members shift from the biochemical oxygen demand (BOD) laboratory test to the quicker, less expensive total organic carbon (TOC) test for permit compliance and process control improvements.

The WEF Laboratory Practices Committee is hosting the no-charge 2-hour webcast, “Using TOC to Replace BOD Requirements,” on Aug. 7 from 1 to 3 p.m. (EDT). Interested members can register online for the webcast, which is sponsored by Shimadzu Scientific Instruments (Columbia, Md.).

The Clean Water Act allows dischargers to replace U.S. Environmental Protection Agency approved BOD-test methods with TOC-test methods to achieve permit compliance. During the webcast, three speakers will discuss their experiences in implementing the change from BOD to TOC testing, including their reasons for making the switch, applying for and receiving state or regulatory approval, and how the switch has benefited their laboratories and plants.

Better process control

While the BOD test — which is used to determine the efficacy of organic-matter removal in the wastewater treatment process — is necessary, it causes several problems for many treatment plants. Test limitations include that BOD testing takes longer for processing a sample than TOC testing — 5 days versus 2 hours, according to speaker Akin Babatola, a laboratory/environmental compliance manager at the Santa Cruz (Calif.) Wastewater Treatment Facility.

“For us, it was important to get BOD results in 2 hours,” Babatola said.

All three speakers said they needed BOD test results much quicker than 5 days for process control. Speaker Nel Groenveld, a laboratory manager at the Inland Empire Utilities Agency in Chino, Calif., said the lag time was the main reason her lab switched to using TOC. Groenveld’s lab, which analyzes samples for three treatment plants ranging from 11,000 to 38,000 m3/d (3 to 10 mgd), has been performing the TOC conversion since the 1970s.

“It has worked very well for us,” Groenveld said. Her lab had to gain approval from a state/regional regulatory board and then the U.S. Environmental Protection Agency for making the switch.

Buy-in from regulators, the facility’s general manager, and operators and other lab staff is necessary, according to Babatola. His lab conducted a study to show equivalence between the two methods and an understanding by facility operators of how to convert their process-handling equations for load wasting and organic-load manipulation, he said.

Better accuracy and cost

BOD testing also poses a challenge in accuracy and precision, especially at low, parts per billion levels that BOD methods cannot read at all, Babatola said, The TOC test procedure has a lower detection limit than BOD — 0.5 mg/L versus 2.0 mg/L.

“These are important factors for beginning to characterize elements of concern if a plant wants to address trace organic compounds in their process and effluent,” Babatola said.

BOD testing also is limited by space constraints; it requires an incubation room. For Babatola’s lab, the need for an incubation room was the main driver for the switch to TOC testing. “My lab simply could not control the temperature in which BOD analysis was done,” he said. The City of Santa Cruz has been able to defer a $180,000 upgrade to its laboratory/administrative building by switching to TOC, Babatola said.

Although TOC involves instruments that require an upfront cost, “the ROI [return on investment] is fast,” Babatola said. “One weekly batch of TOC for a small plant should pay for an average TOC instrument in 1.5 years; two or more BOD refrigerators approximating the same cost will be necessary for the same volume of analyses,” he said. In addition, chemical consumables and electricity needs for BOD are numerous and costly; this is not so for TOC with catalysts, which are renewable, Babatola said.

Webcast participants can earn 2.0 Professional Development Hours for the webcast but should check with their state accreditation agency to determine if they qualify.

Cathy Chang, WEF Highlights

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